Max Einhorn (January 10, 1862 – September 25, 1953) was a Polish American gastroenterologist and inventor of surgical instruments.

[4] Einhorn suggested the concept of Achylia gastrica which has been defined as "a functional perversion of the stomach, characterized by the absence of the gastric secretion (of hydrochloric acid, pepsin, and rennet).

The device would be swallowed by a patient allowing for gastric chemicals to be collected in the container and drawn out of the body for scientific analysis.

The device consisted of a tube with a hollow platinum ball attached, a few electric cells, and a ticker.

[11] As the stomach moved the ball would come into contact with an electrical current which allowed gastric movements to be recorded.